<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>

        <script>
            // 1. 声明一个年龄变量
            let age
            // 2. 变量赋值
            age = 18
            console.log(age)
            // 3. 声明时赋值 也就是初始化
            let name = 18
        </script>
    </body>
</html>